Electrode for lithium battery comprising solid electrolyte nanoparticles and lithium battery

ABSTRACT

A lithium battery electrode body includes: a collector electrode; and an electrode mixture layer in which a plurality of first particles including electrode active material and a plurality of second particles including solid electrolyte are mixed, wherein the electrode mixture layer is provided on one of sides of the collector electrode, and an average particle size of the plurality of second particles is smaller than an average particle size of the plurality of first particles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation patent application of U.S. application Ser. No.12/852,858 filed Aug. 9, 2010, which claims priority to Japanese PatentApplication Nos. 2009-189168, filed Aug. 18, 2009 and No. 2010-173910,filed Aug. 2, 2010, all of which are expressly incorporated by referenceherein in their entireties.

BACKGROUND

1. Technical Field

The present invention generally relates to electrodes for lithiumbatteries and lithium batteries.

2. Related Art

Lithium batteries using lithium or lithium containing material asnegative electrodes are not only light in weight and large in capacity,but also capable of providing high voltages when combined withappropriate positive electrodes. For this reason, lithium batteries arewidely used as batteries for portable electronic equipment, cameras,watches, electric tools, hybrid automobiles and the like. However, suchlithium batteries use highly active lithium and organic electrolyte,which cause for concern about their dangers, such as, firing andexplosion at the time of short-circuits. Therefore, it is an importantissue in designing lithium batteries to secure their safety.

As a method for securing the safety, the use of non-aqueous electrolytemay be enumerated. As an attempt to implement the non-aqueouselectrolyte, lithium polymer batteries that use gel polymer electrolytehave been developed. However, in this attempted method, organicelectrolyte is impregnated in gel polymer, such that the problemsconcerning the limitation of battery cycle life and danger of explosionhave not been solved.

Also, as another attempt to implement the non-aqueous electrolyte,lithium batteries that use ceramic electrolyte (inorganic solidelectrolyte) have been developed (see, for example, Japanese Laid-openPatent Application 2006-277997 (Patent Document 1)). By using theceramic electrolyte, only lithium ions are ions that move in theelectrolyte by the battery reaction and therefore almost no sidereaction occurs. Further, as the ceramic electrolyte does not includeflammable organic solvent, and thus does not need a sealing member or aliquid sealing structure, whereby reduction in size and thickness of thebattery can be achieved.

However, according to the method for powder molding ceramic electrolytepowder with electrode active material powder, as described in PatentDocument 1 as one of the embodiments, insufficient contacts occurbetween the ceramic electrolyte powder and the electrode active materialparticles, and between the ceramic electrolyte powder and the ceramicelectrolyte powder, such that battery power output high enough forpractical use cannot be obtained. Furthermore, the interfacial contactsbecome unstable because of volume changes that take place withcharge-discharge cycles, whereby the battery cycle life is deteriorated.

On the other hand, another type of lithium batteries has been reported(see, for example, Japanese Laid-open Patent Application 2004-179158(Patent Document 2)) in which a vapor phase thin film deposition methodsuch as sputtering is used to form a laminate of layers, such as,positive electrode thin film/ceramic electrolyte thin film/negativeelectrode thin film. According to such a method of laminating thinfilms, good contact can be achieved at interfaces between the electrode(the positive electrode thin film or the negative electrode thin film)and the ceramic electrolyte, and the thickness of the active materiallayer and the electrolyte layer can be reduced, such that high poweroutput and excellent battery cycle life characteristics are expected tobe obtained.

However, according to the method recited in Patent Document 2, the totalthickness of the active material per unit area is only about 1 μm toseveral μm and therefore it is difficult to manufacture batteries withsufficient charge capacity. In other words, in order to obtain asufficient charge capacity as batteries, it is necessary to manufacturebatteries in which the total thickness of active material exceeds 100μm. However, by the method described in Patent Document 2, it isdifficult to obtain the total thickness exceeding 100 μm, such thatbatteries with sufficient charge capacity have not yet beenmanufactured.

SUMMARY

In accordance with an advantage of some aspects of the invention, it ispossible to provide lithium batteries in which their safety can besecured, sufficiently large power output can be obtained, and largecapacity implementation can be achieved, and it is also possible toprovide electrodes for lithium batteries suitable to manufacturing thelithium batteries.

In accordance with an embodiment of the invention, a lithium batteryelectrode body includes a collector electrode, and an electrode mixturelayer in which a plurality of first particles including electrode activematerial particles and a plurality of second particles including solidelectrolyte particles are mixed, wherein the electrode mixture layer isprovided on one of sides of the collector electrode, and an averageparticle size of the plurality of second particles is smaller than anaverage particle size of the plurality of first particles.

According to the lithium battery electrode body described above, theaverage particle size of the plurality of second particles is smallerthan the average particle size of the plurality of first particles,contact points between the electrode active material and the solidelectrolyte per unit volume increase, whereby the contact area at theirinterfaces becomes greater, whereby lithium batteries using suchelectrode bodies can provide greater output, and large capacityimplementation thereof becomes possible. Furthermore, the electrodemixture layer in which the plurality of first particles includingelectrode active material particles and the plurality of secondparticles composed including solid electrolyte particles are mixed isdisposed on one of the sides of the collector electrode, wherebynon-aqueous electrolyte implementation can be achieved, and therefore itbecomes easier to secure the safety of the battery.

In the lithium battery electrode body described above, the electrodemixture layer may preferably be formed by press forming the mixture ofthe plurality of first particles and the plurality of second particles.As a result, fixing of the electrode mixture layer to the collectorelectrode becomes easier, which makes non-aqueous electrolyteimplementation easier.

In the lithium battery electrode body described above, the electrodemixture layer may preferably have the plurality of second particlescovering the plurality of first particles on a side of the electrodemixture layer opposite to a side thereof in contact with the collectorelectrode. As a result, when a lithium battery is manufactured with theelectrode bodies, short-circuit between the positive electrode and thenegative electrode in the lithium battery using the electrode bodies canbe securely prevented by a coating layer of solid electrolyte in whichthe plurality of second particles cover the plurality of firstparticles.

Also, in the lithium battery electrode body described above, an averageparticle size of the solid electrolyte particles in the plurality ofsecond particles may preferably be 100 nm or less. As a result, when aceramic electrode mixture layer is formed by sintering the plurality ofsecond particles and the plurality of first particles, the sinteringtemperature can be lowered. As the sintering temperature is lowered inthis manner, deterioration of the electrode active material particles(the first particles) and degeneration of the conductive particles(conductive agent) and the binder, that may be added if necessary, canbe prevented, and accidental chemical reaction of the aforementionedmaterial can also be prevented.

Also, in the lithium battery electrode body described above, theplurality of second particles may preferably include dielectricparticles having an average particle size of 100 nm or less. As aresult, the ionic conductivity of the electrode active material per unitweight is increased by the so-called interfacial electrical double layereffect, in which an electrical double layer is formed at the interfacebetween the dielectric particles and the other particles, whereby defectdensity is increased.

Also, in the lithium battery electrode body described above, the otherparticles described above are the plurality of second particlesincluding inorganic solid electrolyte, for example.

Also, in the lithium battery electrode body described above, theelectrode mixture layer may preferably be provided with a solidelectrolyte layer on a side opposite to the side thereof in contact withthe collector electrode. As a result, when a lithium battery ismanufactured using the electrode bodies, short-circuit between thepositive electrode and the negative electrode of the lithium batteryusing the electrode bodies can be more securely prevented by the solidelectrolyte layer.

Also, in the lithium battery electrode body described above, organicsolvent or organic electrolytic solution may be impregnated in theelectrode mixture layer. As a result, when a lithium battery ismanufactured using the electrode body, its ionic conductivity becomeshigher by the aid of the organic solvent or the organic electrolyticsolution, resulting in a greater power output.

A lithium battery in accordance with an embodiment of the invention, inthe lithium battery electrode body may be used as a positive electrodeor a negative electrode. According to this lithium battery, contactpoints between the electrode active material and the solid electrolyteper unit volume increase, as described above, and the electrode bodywith an increased contact area at these interfaces is used, wherebyhigher power output and greater capacity can be achieved. Also, the useof the electrode mixture layer makes non-aqueous electrolyteimplementation possible, which makes it easier to secure the safety ofthe battery.

A lithium battery in accordance with another embodiment of the inventionincludes a positive electrode that is formed from the lithium batteryelectrode body having the electrode active material particles beingpositive electrode active material particles, and a negative electrodethat is disposed on the electrode mixture layer of the lithium batteryelectrode body and is formed from metal negative electrode activematerial and a collector electrode. According to this lithium battery,contact points between the electrode active material and the solidelectrolyte per unit volume increase, as described above, and theelectrode body with an increased contact area at these interfaces isused, whereby higher power output and greater capacity can be achieved.Also, the use of the electrode mixture layer makes non-aqueouselectrolyte implementation possible, whereby securing the safety of thebattery becomes easier. Furthermore, the batter is equipped with theelectrode mixture layer containing solid electrolyte, there is noconcern for formation of dendrite, such that, for example, a negativeelectrode composed of lithium metal having a large capacity can be used.

A lithium battery in accordance with still another embodiment of theinvention includes a positive electrode that is formed from the lithiumbattery electrode body having the electrode active material particlesbeing positive electrode active material particles, and a negativeelectrode that is formed from the lithium battery electrode body havingthe electrode active material particles being negative electrode activematerial particles. According to this lithium battery, contact pointsbetween the electrode active material and the solid electrolyte per unitvolume increase, as described above, and the electrode body with anincreased contact area at these interfaces is used, whereby higher poweroutput and greater capacity can be achieved. Also, by the use of theelectrode mixture layer, non-aqueous electrolyte implementation is madepossible, which the safety of the battery can be more readily secured.Furthermore, separators that are required in lithium batteries of therelated art are made unnecessary, such that the number of components isreduced, and therefore the cost can be reduced.

Also, according to any one the lithium batteries described above,organic solvent or organic electrolytic solution may be impregnated inall the electrode mixture layers disposed between the collectorelectrode of the positive electrode and the collector electrode of thenegative electrode. As a result, the ionic conductivity is made higherby the aid of the organic solvent or the organic electrolyte, whichresults in a greater power output.

Also, according to any one of the lithium batteries described above,organic solvent or organic electrolytic solution may be impregnated inthe electrode mixture layer and the solid electrolyte layer disposedbetween the collector electrode of the positive electrode and thecollector electrode of the negative electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side cross-sectional view of a main portion of a lithiumbattery electrode body in accordance with a first embodiment of theinvention.

FIG. 2 is a side cross-sectional view of a main portion of a lithiumbattery electrode body in accordance with a second embodiment of theinvention.

FIG. 3 is a side cross-sectional view of a main portion of a lithiumbattery electrode body in accordance with a third embodiment of theinvention.

FIG. 4 is a side cross-sectional view of a main portion of a lithiumbattery in accordance with a first embodiment of the invention.

FIG. 5 is a side cross-sectional view of a main portion of a lithiumbattery in accordance with a second embodiment of the invention.

FIG. 6 is a side cross-sectional view of a main portion of a lithiumbattery in accordance with a third embodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Embodiments of the invention are described in detail below withreference to the accompanying drawings. First, an electrode for alithium battery (hereafter also referred to as a lithium batteryelectrode) in accordance with an embodiment of the invention isdescribed. FIG. 1 is a side cross-sectional view of a main portion ofthe lithium battery electrode body in accordance with the embodiment ofthe invention. Reference numeral 1 in FIG. 1 denotes a lithium batteryelectrode (hereafter also abbreviated as a battery electrode).

The battery electrode 1 is equipped with a plate-like (or a foil-like)collector electrode 2, and an electrode mixture layer 3 that is incontact with one surface side of the collector electrode 2, and may beused as a positive electrode or a negative electrode of a lithiumsecondary battery (a lithium battery) to be described below. Thecollector electrode 2 is made of a conductive thin plate material (or afoil material), such as, Cu, Ni, Ti, Al, stainless steel, carbon or thelike. The material is suitably selected depending on whether theelectrode body 1 is used as a positive electrode or a negativeelectrode. Also, the collector electrode 2 is connected to a positiveelectrode wiring layer (not shown) or a negative electrode wiring layer(not shown)

Also, the collector electrode 2 may be connected to positive electrodewiring or negative electrode wiring or the like in place of the positiveelectrode wiring layer or the negative electrode wiring layer describedabove.

The electrode mixture layer 3 is made of a molded body formed throughmixing a plurality of first particles 4 composed of inorganic electrodeactive material (electrode active material) and a plurality of secondparticles 5 composed of inorganic electrolyte particles 5 a (solidelectrolyte) to form a mixture, and sintering the mixture in a pressuremolding. As the inorganic electrode active material that form the firstparticles, inorganic positive electrode active material is used when theelectrode body 1 is used as a positive electrode, and inorganic negativeelectrode active material is used when the electrode body 1 is used as anegative electrode.

As the inorganic positive electrode active material, lithium cobaltate(LiCoO₂), lithium nickelate (LiNiO₂), lithium manganate (LiMn₂O₄),lithium titanate (Li₄Ti₅O₁₂) and the like may be used. As the inorganicnegative electrode active material, lithium titanate (Li₄Ti₅O₁₂) and thelike may also be used.

The first particles 4 composed of inorganic electrode active materialmay have an average particle size (diameter) of about 1 μm-10 μm. In itnoted that, in the present invention, the average particle size isdefined as follows. When the electrode mixture layer 3 is cut in anarbitrary plane (which should be a plane where the first particles 4 andthe second particles 5 are present in a mixed state), the averageparticle size is an average value of maximum diameters (maximum lengths)of areas of all of the first particles 4 exposed in the cut surface.

As the plurality of second particles 5 composed of the inorganic solidelectrolyte particles 5 a, the following materials can be used.

(1) Inorganic crystals, inorganic glass or partially crystallized glasshaving lithium ionic conductivity;

(2) NASICON ceramic crystals, such as, LiTi₂ (PO₄)₃, Li_(1.3) M_(0.3)Ti_(1.7) (PO₄)₃ [where M=Al, Sc];

(3) Perovskite ceramic crystals, such as, Li_(0.35) La_(0.55) TiO₃,LiSr₂TiTaO₆, Li_(3x)La_(1/3-x) TaO₃;

(4) Thio-LISICON crystals, such as, Li_(4-x) Si_(1-x) P_(x)S₄, Li_(4-x)Ge_(1-x) P_(x)S₄ and the like;

(5) Silicon crystals, such as, Li₁₄ Zn(GeO₄)₄ or the like;

(6) Li doped β-Al₂O₃ crystals;

(7) Partially crystallized glass including any of the aforementionedcrystals;

(8) Sulfide glass, such as, Li₂ S—SiS₂—LiPO₃ system, Li₂S—P₂S₅ systemglass, or the like;

(9) Oxide glass, such as, Li₂ O—SiO₂—B₂O₃ system, Li₂O—SiO₂—ZrO₂ systemglass, or the like; or

(10) LiPON glass (see, for example, Japanese Laid-open PatentApplication 2004-179158).

Also, as the plurality of second particles 5, the following materialscan be preferably used.

(11) LiI crystals;

(12) Li₃PO₄ crystals; or

(13) Garnet-type crystals, such as Li₇La₃Zr₂O₁₂.

The plurality of second particles 5 composed of such inorganic solidelectrolyte particles 5 a may have an average particle size of about 100nm or less, which is a common diameter of nanoparticles, and preferablyabout 50 nm. In other words, in accordance with the invention, as theplurality of second particles 5, it is preferred to use particles havingan average particle size substantially smaller than the average particlesize of the plurality of first particles 4, which is about one hundredth( 1/100) or less of the average particle size of the plurality of firstparticles 4. As a result, contact points between the inorganic electrodeactive material (the first particles 4) and the inorganic solidelectrolyte (the inorganic solid electrolyte particles 5 a) per unitvolume increase in the electrode mixture layer 3, whereby the contactarea at their interfaces becomes greater.

Also, as the average particle size of the plurality of second particles5 composed of the inorganic solid electrolyte particles 5 a is set to beabout 100 nm or less, the sintering temperature at the time of moldingthe electrode mixture layer 3, as described below, can be lowered. It isnoted that, the average particle size is also defined as follows. Whenthe electrode mixture layer 3 is cut in an arbitrary plane (which shouldbe a plane where the first particles 4 and the second particles 5 arepresent in a mixed state), the average particle size is an average valueof maximum diameters (maximum lengths) of areas of all of the secondparticles 5 (the inorganic solid electrolyte particles 5 a) exposed inthe cut surface, like the average particle size of the first particles 4described above.

Also, the inorganic solid electrolyte particles 5 a (the secondparticles 5) described above may be formed by any one of the followingknown methods, such as, a mechanical milling method, a hydrothermalsynthesis method, a supercritical hydrothermal synthesis method, amicro-emulsifying method, RESS (Rapid Expansion of SupercriticalSolution) method, PGSS (Particles from Gas Saturated Solutions) method,GAS (Gas Anti-Solvent Re-crystallization) method, SEDS(Solution-Enhanced Dispersion of Solids) method and the like. Above all,the hydrothermal synthesis method is preferred.

Also, in accordance with the present embodiment, an additive 6 composedof binder particles or conductive particles (conducting agent) is addedin the electrode mixture layer 3. As the binder particles, particlescomposed of, for example, styrene system thermoplastic elastomer,polyolefin, polyamide, polyimide or the like. As the conductingparticles, for example, carbon particles can be used. The mixing ratiobetween the first particles 4 and the second particles 5 (the inorganicsolid electrolyte particles 5 a) in the electrode mixture layer 3 is notparticularly limited, but may be about 2:8-8:2 in weight ratio. Also,the mixing ratio (mixing proportion) of the total of binder particlesand conducting particles in the electrode mixture layer 3 may be about2-30% in weight ratio.

For the preparation of the electrode mixture layer 3, the firstparticles 4 and the second particles 5 (the inorganic solid electrolyteparticles 5 a) are mixed in a suitable mixing ratio, and then binderparticles and conducting particles in a suitable mixing ratio are addedand mixed together. The mixture is filled in a shaping mold, and heatedand pressed in a manner similar to an ordinary pellet molding, wherebythe electrode mixture layer 3 in a desired configuration (for example, arectangular parallelepiped configuration) is obtained. The moldingpressure and the molding temperature are appropriately set according tothe kinds and the mixing ratio of the particles to be used, the kind andthe amount of binder and the like. It is noted that, as the averageparticle size of the inorganic solid electrolyte particles 5 a is about100 nm or less, the sintering temperature at the time of molding theelectrode mixture layer 3 can be lowered, whereby deterioration of theinorganic solid active material particles 5 a, the conducting particles(conducting agent) and the binder can be prevented, and accidentalchemical reaction of the aforementioned materials can also be prevented.

Also, with the electrode mixture layer 3 formed in this manner, theplurality of second particles 5 cover the plurality of first particles 1on the opposite side of the side thereof that contacts the collectorelectrode 2. In other words, on the opposite side of the collectorelectrode 2, a coating layer 7 composed of the second particles 5(inorganic solid electrolyte particles 5 a) is formed. The coating layer7 may preferably be 50 nm or more in thickness, more preferably 200 nmor more in thickness. By forming such a coating layer 7, when a lithiumbattery is manufactured using the electrode body 1 as described below,short-circuit between the positive electrode and the negative electrodecan be securely prevented by the coating layer 7.

Then, the electrode mixture layer 3 obtained in this manner is broughtin contact and affixed (bonded) with the collector electrode 2 with thecoating layer 7 facing outward, whereby the electrode body 1 shown inFIG. 1 is obtained. In the electrode body 1, the average particle sizeof the plurality of second particles 5 is smaller than the averageparticle size of the plurality of first particles 4, contact pointsbetween the inorganic electrode active material and the inorganic solidelectrolyte per unit volume increase in the electrode mixture layer 3,whereby the contact area at their interfaces becomes greater.Accordingly, lithium batteries using such electrode bodies 1 can providegreater power output, and large capacity implementation thereof becomespossible. Furthermore, the electrode mixture layer 3 in which theplurality of first particles 4 composed of inorganic electrode activematerial and the plurality of second particles 5 having inorganic solidelectrolyte particles are mixed is disposed on one of the sides of thecollector electrode 2, whereby non-aqueous electrolyte implementationcan be achieved in lithium batteries using the electrodes, and thereforethe safety of the batteries can be more readily secured.

FIG. 2 is a side cross-sectional view of a main portion of a lithiumbattery electrode body in accordance with a second embodiment of theinvention. Reference numeral 10 in FIG. 2 denotes a lithium batteryelectrode body (hereafter referred to an electrode body). The electrodebody 10 is different from the electrode body 1 shown in FIG. 1 in thatthe plurality of second particles 5 include dielectric particles 5 b, inaddition to the inorganic solid electrolyte particles 5 a.

The dielectric particles 5 b are composed of dielectric material suchas, Al₂O₃, TiO₂ or the like, and has an average particle size of about100 nm or less, like that of the inorganic solid electrolyte particles 5a described above, and more preferably about 50 nm. The dielectricparticles 5 b may be included by about 1-50 mol %, and more preferablyabout 8 mol % in the entire second particles 5, in other words, thesecond particles 5 composed of the inorganic solid electrolyte particles5 a and the dielectric particles 5 b.

In this manner, the electrode body 10 in accordance with the presentembodiment has the dielectric particles 5 b added in the secondparticles 5, the ionic conductivity of the inorganic electrode activematerial per unit weight is increased by the interfacial electricaldouble layer effect, whereby lithium batteries using the electrodebodies 10 can provide greater power output. It is noted that, when themixing ratio of the dielectric particles 5 b in the second particles 5is less than 1 mol %, almost no interfacial electrical double layereffect can be obtained, such that the ionic conductivity cannot beimproved. On the other hand, when the mixing ratio exceeds 50 mol %, theionic conductivity of the entire electrode mixture layer 3 including thesecond particles is lowered, which is not desirable.

FIG. 3 is a side cross-sectional view of a main portion of a lithiumbattery electrode body in accordance with a third embodiment of theinvention. Reference numeral 20 in FIG. 3 denotes a lithium batteryelectrode body (hereafter referred to an electrode body). The electrodebody 20 is different from the electrode body 1 shown in FIG. 1 in thatan inorganic solid electrolyte layer 21 is provided on the coating layer7 of the electrode mixture layer 3, in other words, on the side oppositeto the side of the electrode mixture layer 3 that is in contact with thecollector electrode 2.

The inorganic solid electrolyte layer 21 may be made of substantiallythe same material as any one of the materials for the inorganic solidelectrolyte particles 5 a shown in (1)-(10) and (11)-(13) above.Inorganic solid electrolyte particles 5 a pre-formed into a sheet shape(or a foil shape), or a commercially available inorganic solidelectrolyte sheet may be used. Also, the inorganic solid electrolytelayer 21 that is thin enough without deteriorating the ionicconductivity may be used. For example, the inorganic solid electrolytelayer 21 that is formed in a sheet shape (a foil shape) of 2 mm or lessin thickness, or more preferably 20 μm or less in thickness maypreferably be used. The inorganic solid electrolyte layer 21 is placedin a shaping mold together with a mixture of the first particles 4 andthe second particles 5, for example, when the electrode mixture layer 3is shaped into a formed body by a hot-press method. Then, byhot-pressing the inorganic solid electrolyte layer 21 together with themixture, the inorganic solid electrolyte layer 21 is formed in one piecewith and on one side of the electrode mixture layer 3 (on the coatinglayer 7), as shown in FIG. 3.

Because the electrode body 20 is provided with the inorganic solidelectrolyte layer 21, when a lithium battery is manufactured with theelectrode body 20, short-circuit between the positive electrode and thenegative electrode can be more securely prevented.

It is noted that, in accordance with the third embodiment, the electrodemixture layer 3 uses the same structure as that of the electrode mixturelayer 3 shown in FIG. 1. However, as the inorganic solid electrolytelayer 21 is provided, the electrode mixture layer 3 without the coatinglayer 7 formed therein may be used. Also, as the electrode mixturelayer, the one with the plurality of second particles 5 containing thedielectric particles 5 b, as shown in FIG. 2, may also be used.

Furthermore, organic solvent or organic electrolyte solution may beimpregnated in the electrode mixture layer 3. As the organic solvent,ethylene glycol or the like may be used. As the organic electrolytesolution, a saturated solution in which lithium chloric acid isdissolved in ethylene glycol is preferably used. In order to impregnateorganic solvent or organic electrolyte solution in the electrode mixturelayer 3, the electrode mixture layer 3 may have been hot pressed into aporous state. As a result, micro gaps (pores) are formed between thefirst particles 4 and the second particles 5, and the organic solvent orthe organic electrolyte solution is impregnated and stored in the pores.When a lithium battery is manufactured with such an electrode body, theionic conductivity in the electrode mixture layer 3 can be made higherby the aid of the organic solvent or the organic electrolyte solution,whereby the lithium battery obtained can provide higher power output.

As the organic solvent, ethylene carbonate may be used. As the organicelectrolyte solution, a saturated solution in which lithiumhexafluorophosphate or lithium chloric acid is dissolved in ethylenecarbonate or ethylene glycol can be preferably used. Also, apress-method may be applied in place of the hot-press method describedabove.

Next, a lithium battery in accordance with an embodiment of theinvention is described. The lithium battery in accordance with thepresent embodiment uses the lithium battery electrode 1 (or 10 or 20)describe above as a positive electrode or a negative electrode. FIG. 4is a side cross-sectional view of a main portion of the lithium batteryin accordance with a first embodiment of the invention, and referencenumeral 30 in FIG. 4 denotes the lithium battery.

The lithium battery 30 uses the electrode body 20, that is shown anddescribed above in FIG. 3 as the electrode body (the lithium batteryelectrode body), on the side of a positive electrode 31. The electrodebody 20 includes a collector electrode 2 and an inorganic solidelectrolyte layer 21 on the opposite side of the collector electrode 2.Also, a metal negative electrode active material 32 and a collectorelectrode 33 are laminated in this order on the inorganic solidelectrolyte layer 21 as a negative electrode 34. In the electrode body20 used as the positive electrode 31, positive electrode active materialis used as the inorganic electrode active material forming the firstparticles 4. As the metal negative electrode active material 32, lithiummetal, Li—In alloy, Li—Al alloy or the like is used. Also, the collectorelectrode 33 may use the same kind of material as that of the collectorelectrode 2 of the electrode body 1 (or 10 or 20).

Then, the electrode body 20, the metal negative electrode activematerial 32 and the collector electrode 33 are laminated and placed in ashaping mold, and the entire laminate is press formed into one piece,whereby the lithium battery 30 is obtained. It is noted that a positiveelectrode wiring layer (not shown) is connected to the collectorelectrode 2 on the side of the positive electrode 31, and a negativeelectrode wiring layer (not shown) is connected to the collectorelectrode 33 of the negative electrode 34.

Also, alternatively, in place of the positive electrode wiring layer orthe negative electrode wiring layer described above, positive wiring canbe connected to the collector electrode 2 on the side of the positiveelectrode 31 and negative wiring can be connected to the collectorelectrode 33 on the side of the negative electrode 34.

According to this lithium battery 30, contact points between theinorganic electrode active material and the inorganic solid electrolyteper unit volume increase, as described above, and the electrode body 20with an increased contact area at these interfaces is used, wherebyhigher power output and greater capacity can be achieved. Also, the useof the electrode mixture layer 3 makes non-aqueous electrolyteimplementation possible, which makes it easier to secure the safety ofthe battery. Furthermore, because the inorganic solid electrolyte layer21 is disposed between the electrode mixture layer 3 on the side of thepositive electrode 31 and the negative electrode 34, short-circuitbetween the positive electrode 31 and the negative electrode 34 can bemore securely prevented.

FIG. 5 is a side cross-sectional view of a main portion of a lithiumbattery in accordance with a second embodiment of the invention, andreference numeral 40 in FIG. 5 denotes the lithium battery. The lithiumbattery 40 is different from the one shown in FIG. 4 in that theelectrode body 20 shown in FIG. 3 is used not only on the side of thepositive electrode 31 but also on the side of the negative electrode.More specifically, the lithium battery 40 is formed through joining theinorganic solid electrolyte layer 21 in the electrode body 20 on theside of the positive electrode 31 with the inorganic solid electrolytelayer 21 in the electrode body 20 on the side of the negative electrode41. The electrode body 20 used on the side of the positive electrode 31uses positive electrode active material as the inorganic electrodeactive material that forms the first particles 4, and the electrode body20 used on the side of the negative electrode 41 uses negative electrodeactive material as the inorganic electrode active material that formsthe first particles 4.

Accordingly, in the lithium battery 40, contact points between theinorganic electrode active material and the inorganic solid electrolyteper unit volume increase, and the electrode bodies 20 with an increasedcontact area at these interfaces are used, whereby higher power outputand greater capacity can be achieved. Also, the use of the electrodemixture layer 3 enables non-aqueous electrolyte implementation, wherebythe safety can be more readily secured. Furthermore, because theinorganic solid electrolyte layer 21 is disposed between the electrodemixture layer 3 on the side of the positive electrode 31 and theelectrode mixture layer 3 on the side of the negative electrode 41,short-circuit between the positive electrode 31 and the negativeelectrode 41 can be more securely prevented. Furthermore, separatorsthat are required in lithium batteries of the related art are madeunnecessary, such that the number of components is reduced, andtherefore the cost can be reduced.

In the lithium battery 40, the electrode bodies 20 shown in FIG. 3 areused on both of the positive electrode side and the negative electrodeside. However, the electrode body 20 shown in FIG. 3 may be used on oneof the sides, and the electrode body 1 shown in FIG. 1 or the electrodebody 10 shown in FIG. 2 may be used on the other side. Also, in thelithium batteries 30 and 40 shown in FIGS. 4 and 5, the electrode body20 equipped with the electrode mixture layer 3 having the coating layer7 is used. However, an electrode body equipped with the electrodemixture layer without the coating layer 7 may also be used, as theinorganic solid electrolyte layer 21 is disposed between the positiveelectrode side and the negative electrode side.

Furthermore, like a lithium battery 50 in accordance with a thirdembodiment shown in FIG. 6, electrode bodies 1 shown in FIG. 1 may beused as both the positive electrode and the negative electrode, orelectrode bodies 10 shown in FIG. 2 may be used as both the positiveelectrode and the negative electrode. In the lithium battery 50 havingsuch a structure, the electrode body 1 (10) equipped with the electrodemixture layer 3 having the coating layer 7 is used, such thatshort-circuit between the positive electrode and the negative electrodecan be securely prevented.

Also, in the lithium battery 30 (40 and 50) shown in FIGS. 4-6,respectively, organic solvent or organic electrolyte solution may beimpregnated in all the electrode mixture layers between the collectorelectrode of the positive electrode and the collector electrode of thenegative electrode. In this case, the lithium battery may be assembled,using the electrode body in which organic solvent or organic electrolytesolution has been impregnated in advance in the electrode mixturelayers. Alternatively, organic solvent or organic electrolyte solutionmay be impregnated in the electrode mixture layers of the lithiumbattery 30 (40 or 50) which has been assembled in the state shown inFIGS. 4-6.

Also, in the lithium battery 30 (40 and 50) shown in FIGS. 4-6,respectively, organic solvent or organic electrolyte solution may beimpregnated in the electrode mixture layer and the inorganic solidelectrolyte layer disposed between the collector electrode of thepositive electrode and the collector electrode of the negativeelectrode. In this case, the lithium battery may be assembled, using theelectrode body in which organic solvent or organic electrolyte solutionhas been impregnated in advance in the electrode mixture layers.Alternatively, organic solvent or organic electrolyte solution may beimpregnated in the electrode mixture layers of the lithium battery 30(40 or 50) and the inorganic solid electrolyte layer which have beenassembled in the state shown in FIGS. 4-6

As a result, the ionic conductivity in the electrode mixture layer canbe made higher by the aid of the organic solvent or the organicelectrolyte solution, such that the lithium battery can provide greaterpower output. It is expected that the lithium battery in accordance withany one of the embodiments of the invention can provide 200 Wh or higheras a single cell that particularly emphasizes its safety, and 100 Wh orhigher as an assembled battery.

Also, the ionic conductivity in the inorganic solid electrolyte layercan be made higher, such that the lithium battery can provide greaterpower output.

Also, the lithium batteries in accordance with any one of theembodiments of the invention can be used in portable electronicequipment such as mobile phones and notebook computers, electricvehicles and the like. Furthermore, the lithium batteries in accordancewith any one of the embodiments of the invention can be used in aimplantable device to be implanted in a body of a patient, whichparticularly emphasizes the safety, such as, a neurological stimulationdevice, a cardiac defibrillator, a cardiac pacemaker, a cardiaccontractility module, a cardiac contractility modulator, a cardioverter,a drug delivery device, a cochlear implant, a hearing aid, a sensor, atelemetry device, and a diagnostic recorder.

The lithium battery electrode bodies and lithium batteries in accordancewith the invention are not limited to those described in theembodiments, and many changes can be made within the range that does notdepart from the subject matter of the invention. For example, in each ofthe embodiments described above, the electrode mixture layer is disposedon one of the sides of the collector electrode. However, the electrodemixture layers may be provided on both sides of the collector electrode,and the solid electrolyte may be disposed in a manner to surround theelectrode mixture layer in accordance with another embodiment. Such anembodiment is also within the applicable range of the invention.

What is claimed is:
 1. An electrode body for a lithium batterycomprising: a collector electrode; and an electrode mixture layer thatincludes a mixture of a plurality of first particles, a plurality ofsecond particles and a plurality of third particles as additives, eachof the plurality of first particles containing an electrode activematerial and each of the plurality of second particles containing asolid electrolyte, the electrode mixture layer being disposed on oneside of the collector electrode, and an average particle size of theplurality of second particles being smaller than an average particlesize of the plurality of first particles; wherein the average particlesize of the plurality of second particles is 100 nm or less; and whereinthe weight ratio of the plurality of third particles in the electrodemixture layer is 2-30%.
 2. An electrode body of lithium batteryaccording to claim 1, the electrode mixture layer being formed from amixture of the plurality of first particles and the plurality of secondparticles by a press forming method.
 3. An electrode body of lithiumbattery according to claim 1, the plurality of second particles coveringthe plurality of first particles on one side of the electrode mixturelayer, another side of the electrode mixture layer that is opposite tothe one side contacting with the collector electrode.
 4. An electrodebody of lithium battery according to claim 1, the plurality of secondparticles including a plurality of dielectric particles having anaverage particle size of 100 nm or less.
 5. An electrode body of lithiumbattery according to claim 1, a solid electrolyte layer being disposedon one side of the electrode mixture layer, another side of theelectrode mixture that is opposite to the one side contacting with thecollector electrode.
 6. An electrode body of lithium battery accordingto claim 1, organic solvent or organic electrolytic solution beingimpregnated in the electrode mixture layer.
 7. An electrode body oflithium battery according to claim 1, the plurality of third particlescomposed of binder particles or conductive particles.
 8. A lithiumbattery comprising the electrode body of lithium battery according toclaim 1, the electrode body used as a positive electrode or a negativeelectrode.
 9. A lithium battery comprising: a positive electrodeincluding the electrode body of lithium battery according to claim 1,the electrode active material including a positive electrode activematerial; and a negative electrode that is disposed on the electrodemixture layer of the electrode body of lithium battery, the negativeelectrode including metal negative electrode active material and acollector electrode.
 10. A lithium battery comprising: a positiveelectrode including the electrode body of lithium battery according toclaim 1, the electrode active material including a positive electrodeactive material; and a negative electrode including the electrode bodyof lithium battery according to claim 1, the electrode active materialincluding a negative electrode active material.
 11. A lithium batteryaccording to claim 8, organic solvent or organic electrolytic solutionbeing impregnated in the electrode mixture layer, the electrode mixturelayer being disposed between the collector electrode of the positiveelectrode and the collector electrode of the negative electrode.
 12. Alithium battery according to claim 8, organic solvent or organicelectrolytic solution being impregnated in the electrode mixture layerand a solid electrolyte layer, the electrode mixture layer beingdisposed between the collector electrode of the positive electrode andthe collector electrode of the negative electrode.